Shielded wire stripper



June 20, 1961 E. E. FOLKENROTH ET AL 2,988,940

SHIELDED WIRE STRIPPER 3 Sheets-Sheet 1 Filed Dec. 31, 1958 INVENTORS 'EIQTI FMkenrorh and UJilbur Y Havdemcnn June 20, 19 1 E. E. FOLKENROTH ET AL 2,988,940

SHIELDED WIRE STRIPPER 3 Sheets-Sheet 2 Filed Dec. 31, 1958 r fl IN VENTORS lbuTY'Hmrdeman my; m

June 20, 1961 E. E. FOLKENROTH ET AL 2,938,940

SHIELDED WIRE STRIPPER Filed Dec. 51, 1958 3 Sheets-Sheet 3 L JL Tee INVENTORS Ion-l (i. F'olkenroth and wilburYfiurdevnan W W r W cannot be removed from the conductor.

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2,988,940 SHIELDED WIRE STRIPPER 'Earl E. Folkenroth, Paxtang, and Wilbur Y. Hardeman,

Carlisle, Pa., assignors to AMP Incorporated, Harrisburg, Pa.

Filed Dec. 31, 1958, Ser. No. 784,259 2 Claims. (Cl. 81-951) This invention relates to methods and apparatus for removing a portion of a tubular covering or sheath from a relatively elongated member such as a wire or cable. In the description which follows, an embodiment of the invention is described which is particularly adapted to the removal of braided metallic shielding from an electrical conductor, however, the invention is amenable to other uses such as the removal of some types of insulation from wires.

Shielded conductors are commonly provided in the form of one or more service wires having insulation coverings thereover and having a metallic braided shielding sheath, composed of a large number (eg. 50 or more) of very fine steel wires around the insulation. The fine wires of this braiding are wrapped helically, some in the clockwise and some in the counterclockwise direction, and intertwined over and under each other to form the tubular shielding sheath. The removal of this metallic brading from the conductors for purposes of splicing or terminating the wires has presented a vexatious problem in the past for several reasons. For example, every one of the numerous small steel wires which make up the braided shielding must be severed, and if only a few of these wires are not severed, the cut section of shielding Furthermore, these fine steel wires resist severing by ordinary methods which are applicable to conventional types of wire insulation. If it is attempted to sever these fine wires by cutting radially toward the axis of the shielded conductor, at least some of the strands will tend to yield before the cutting edge used and will not be severed, probably because of the fact that these wires are supported during the cutting by the insulation of the service wires. If the cut into the shielding is made relatively deep so as to insure severing of all the small wires of the shielding, there is a danger of cutting into the insulation surrounding the service wires of the conductor and even severing the service wires themselves. A further characteristic of the shielding which renders the removal thereof a diflicult operation is that if a section of shielding is circumferentially severed from the main body of shielding and it is attempted to pull the severed section from the end of conductor, the severed section tends to increase in length and decrease in diameter so that it is tightened around the insulated service conductors and resists removal.

It has been common in the past to remove the shielding from the end of a shielded conductor by cutting axially along the shielding up to the limit desired and then cutting circumferentially so that the removed section of shielding need not be pulled or slid axially over the end of the wire. This technique is extremely time consuming and requires careful work on the part of the operator in order to avoid damage to the service wires of the conductor.

An object of the present invention is then to provide an improved method and apparatus for removing a tubular covering from a relatively elongated member such as a wire or cable. A further and more specific object is to provide a method and apparatus for removing metallic braid shielding from the'end of a shielded wire conductor.

A preferred apparatus in accordance with the invention provides a pair of sleeve-like members having substantially the same internal and external diameters, and a shearing slide which is coaxially disposed with respect to the sleeve-like members and axially movable thereover. A sheath engaging means is also provided which engages the end of the sheath or covering which is to be removed and this sheath engaging means and one of the sleeve-like members are movable towards the other sleevelike member. Upon such movement, with a wire extending through the sleeves, a portion of the sheath material is gathered and a collar of the sheath material is formed and clamped between the faces of the sleevelike members. The shearing slide then moves over and past this collar to shear it around its periphery. The cut element of sheath material can then be removed by sliding it over and off the wire. This element does not resist such removal since its internal diameter is somewhat enlarged by the gathering step which precedes cutting.

In the drawing:

FIGURE 1 is a top plan view of a preferred form of apparatus in accordance with the invention;

FIGURE 2 is a perspective view of the apparatus of FIGURE 1;

FIGURE 3 is a view taken along the line 3-3 of FIGURE 1;

FIGURES 4, 5 and 6 are fragmentary views similar to FIGURE 3 but showing the apparatus in several stages of its operating cycle;

FIGURE 7 is a perspective view of one type of shielded wire conductor; and

FIGURE 8 is a plan view of an alternative embodiment.

Referring first to FIGURE 7, a common type of shielded wire conductor comprises one or more service conductors 2, each having an insulating covering 4 thereover which may be of any of the commonly known materials used for this purpose, for example a vinyl plastic. A braided shielding sheath 6, composed of a large number of fine steel wires helically wrapped around the interconductors 2, 4 and overlapped and underlapped with each other, extends coaxially along the cable for its full length. It will be understood that in FIGURE 7 the shielding has been stripped back but that the conductor as supplied has a shielding sheath extending throughout its length. In many instances an outer covering of insulating material of vinyl or the like 8 is also provided to insulate the metallic braid shielding and to protect it from mechanical wear or damage. The removal of this outer insulating covering 8 poses no particular problem since it can be stripped by circumferential cutting in the conventional and known manner.

Referring now to FIGURES 1, 2 and 3 a preferred apparatus in accordance with the invention comprises a mounting plate 10 on which is mounted a support member 12 having an axial bore 14 extending therethrough. The diameter of this bore should be sufiicient freely to receive the conductor although it should not be grossly oversized. In other words, it should be possible for the operator to insert the conductor through this bore without undue difficulty. The left end of this bore, as viewed in FIGURE 3, is counterbored and receives an insert or bushing 18 having an inside diameter 19 which is substantially the same as the diameter of the bore 14. The end of this bushing however has a smaller diameter as indicated at 2 2 to define a shoulder 20 which functions as a stop for the conductor and which bears against the cut face of the outer vinyl insulation covering 8 when the wire is inserted. The inside diameter 22 of the bushing should be sufliciently large freely to receive the shielded conductor with the outer vinyl covering removed but again it should not be unduly oversized. It will also be noted that the end of bushing 18 extends as indicated at 24 beyond support member 12 and defines a sleeve in surrounding relationship to the shielded conductor.

Spaced from support 12 and mounted on plate is a housing 26 having an axial passage through which a shearing slide member 28 is movable towards and away from support member 12. Any suitable means for reciprocating this shearing slide may be provided, the disclosed embodiment having a pivotal connection 30 with the end of a piston rod 32 extending from a pneumatic cylinder 34. Slide member 28 has an axial bore in substantial alignment with the bore 14 of support 12 and in this bore there is secured, as by a press fit and a set screw 37, an adapter or insert 36. This adapter in turn is axially bored and receives a gathering slide member 38 having a reduced outside diameter end 39 which projects beyond the end of insert 36 and forms a sleeve which surrounds the wire. Interengaging shoulder means 48 on the gathering slide and the insert 36 limits rightward movement of this gathering slide relative to the shearing slide. A bushing 40 is press fitted or otherwise secured in the left end of the gathering slide and this bushing has an internal diameter 41 such that its face 43 will bear against the metallic braid shielding when a wire is inserted as shown in FIGURE 4 and will function as a sheath engaging means, although the service conductors and their insulating coverings will be in alignment with bore 41 and will not bear against this face. It will be noted that the internal diameter of gathering slide 39 is reduced at its end at although again, the diameter at this zone should be suflicient relatively freely to receive the shielded conductors. Intermediate its ends the diameter of the bore in this slide is somewhat greater than the diameter of the shielded wire to permit gathering or bunching of the shielding as explained below and to facilitate insertion of the wire during operations.

Gathering slide 38 is normally biased rightwardly and against shoulder 48 by means of a spring 42 which is received within the bore of the slide 28 and this spring in turn bears against a plug or stop generally indicated at 44 and secured and held in place by means of a set screw 46. It will thus be apparent that this slide member 38 can be moved leftwardly relative to slide 28 against the compression of this spring.

In use, a shielded conductor, with the outer vinyl covering stripped back to the desired point, is inserted through the aligned bores 14, 19, 22, 50 and 52 until the cut face of the vinyl covering 8 is brought to bear against shoulder 20. The operator then merely holds the conductor at the right of support 12 as viewed in FIGURE 3 and actuates air cylinder 34 to drive shearing slide 28 rightwardly. During such rightward movement of this slide, the face 43 of bushing 40 moves against and engages the face of the shielding and pushes it rightwardly thereby gathering a portion of this shielding in the section 52 of slide 38 to form a gathered bulge indicated at 6A in FIGURE 5. As previously mentioned, this metallic braided shielding does not resist axial pushing but tends to bulge somewhat during such pushing. Also during this initial movement of the slide member, a small bulge indicated at 63 might be formed between the projecting portion 39 of slide 38 and the projecting portion 24 of bushing 16. Upon further rightward movement of the slide, this gathered section at 6B forms a radially extending collar of braiding wires as shown in FIGURE 6. This collar may be formed in part from braiding material which is drawn from the gathered portion 6A of FIGURE 5 since it is possible to pull the braiding from a bulge of the type shown at 6A. The collar 6C as shown in FIGURE 6 is clamped between the opposed faces of sleeve-like projections 24 and 39 and held tightly around its entire periphery while the shearing slide moves from the solid line position of FIGURE 6 to the dotted line position shown. Gathering slide 38 .during this interval-is held tightly against the collar by virtue of spring 42 and while thus held or 4 clamped, the periphery of the collar 60 is sheared away by the slide which functions as a shear.

Upon return of the slide member 28 leftwardly from the position of FIGURE 6 to the position of FIGURE 3, the conductor can be withdrawn rightwardly by the operator and the cut section of shielding will not tend to grip the service conductors 4 since this section has been gathered and its internal diameter increased along a substantial portion of its length as indicated at 6A. After removal of the conductor from the support member 12, the severed section of shielding can be removed digitally or if desired by a mechanical finger or bushing device.

FIGURE 8 shows an alternative embodiment in which support 12 is replaced by a clamping member 54 comprising a pair of blocks 56, '58 having grooves 60 in their opposed surfaces to define a passageway for the conductor when the blocks are moved against each other. Block 58 is mounted on the end of a piston rod 64 of a pistoncylinder 66 and is guided during movement towards block 56 by means of guide pins 62. In use, the blocks are normally spaced apart as shown and the wire is first positioned between them in alignment with grooves 60. Thereafter, piston-cylinder 66 is actuated to cause block 58 to move towards block 56 to clamp the conductor and the sheath is then removed as previously described.

It may be found that with some types of wire coverings it is desirable to employ the clamping arrangement of FIGURE 8, however, where relatively loose metallic braiding is being removed, the arrangement of FIGURES l-6 (of merely supporting the conductor in the passageway of the support block) has been found to be satisfactory. It should be pointed out that it is not necessary under all circumstances to form the gathered portion 6A in FIGURE 5 before forming the collar indicated at 6C. Where a relatively short length of shielding is being re moved from the end of the wire it is possible to form the collar 6C directly from shielding gathered at the end portion of the conductor and without forming the gathered portion 6A. If this method is employed, the apparatus can be somewhat more simple than the embodiment of FIGURE 1 in that the gathering slide can be relatively short and need not have the enlarged diameter portion 52.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective against the prior art.

We claim:

1. Apparatus for removing a portion of a cylindrical sheath from a wire comprising, wire supporting means including a sleeve, a shearing slide movable relatively towards and away from said sleeve, a gathering slide carried by said shearing slide and having an axial passageway extending therethrough in alignment with said sleeve, the internal diameter of said sleeve and the diameter of the end portion of said passageway adjacent to said sleeve being sufliciently large freely to receive said wire in relatively closely embracing relationship, a sheath engaging shoulder in said passageway, an enlarged diameter section in said passageway between said shoulder and said end portion, said gathering slide being axially movable relative to said shearing slide, and biasing means in said shearing slide for normally biasing said gathering slide towards said sleeve but permitting relative motion between said gathering slide and said shearing slide, whereby, upon insertion of a sheathed wire through said sleeve and into said passageway, and upon initial movement of said shearing slide, said shoulder engages said sheath and gathers a section thereof in said enlarged diameter section,. a nd the section of sheath'in the'zone between said sleeve and said gathering slide is also gathered to form a radical collar, and said collar is subsequently clamped between said gathering and shearing slides and is thereafter sheared as said shearing slide moves relatively thereover.

2. Apparatus for removing a portion of a cylindrical covering from a wire comprising a sleeve, a shearing slide movable relatively towards and away from said sleeve, a gathering slide carried by said shearing slide and having an axial passageway extending therethrough in alignment with said sleeve, the internal diameter of said sleeve and the diameter of said passageway being sufliciently large freely to receive said wire, said gathering slide being axially movable relative to said shearing slide, means for normally biasing said gathering slide relative to said shearing slide towards said sleeve but permitting relative motion between said gathering slide and said shearing slide,

means for moving said shearing slide relatively towards said sleeve, and engaging means movable with said shearing slide for engaging said covering during movement of said shearing slide towards said sleeve whereby, said covering is gathered in the zone between said gathering slide and said sleeve to form a collar of covering material, and said collar is clamped between said gathering slide and said sleeve when said gathering slide comes to rest, and said shearing slide thereafter moves over said gathering slide towards said sleeve to shear said collar.

References Cited in the file of this patent UNITED STATES PATENTS 

